Moved serialization out of CRWSessionEntry.

ios/web/BUILD.gn

Index: ios/web/BUILD.gn
diff --git a/ios/web/BUILD.gn b/ios/web/BUILD.gn
index b4caf9eb0530ad91052d75e5c231d34a1604bcb4..a9313b8edd944ea4bd608374bcae4e97603d194b 100644
--- a/ios/web/BUILD.gn
+++ b/ios/web/BUILD.gn
@@ -60,6 +60,8 @@ source_set("web_arc") {
     "navigation/navigation_item_facade_delegate.h",
     "navigation/navigation_item_impl.h",
     "navigation/navigation_item_impl.mm",
+    "navigation/navigation_item_storage_builder.h",
+    "navigation/navigation_item_storage_builder.mm",
     "navigation/navigation_manager_delegate.h",
     "navigation/navigation_manager_facade_delegate.h",
     "navigation/navigation_manager_impl.h",
@@ -97,6 +99,8 @@ source_set("web_arc") {
     "public/browser_url_rewriter.h",
     "public/cert_policy.h",
     "public/certificate_policy_cache.h",
+    "public/crw_navigation_item_storage.h",
+    "public/crw_navigation_item_storage.mm",
     "public/crw_navigation_manager_storage.h",
     "public/crw_navigation_manager_storage.mm",
     "public/favicon_status.cc",
@@ -514,6 +518,7 @@ test("ios_web_unittests") {
     "active_state_manager_impl_unittest.mm",
     "browser_state_unittest.cc",
     "history_state_util_unittest.mm",
+    "navigation/crw_navigation_item_storage_unittest.mm",
     "navigation/crw_session_controller_unittest.mm",
     "navigation/crw_session_entry_unittest.mm",
     "navigation/navigation_item_impl_unittest.mm",